SAN FRANCISCO, Oct 4 (Reuters) - D-Wave Systems, a Vancouver-based company that aims to develop quantum-computing applications, said on Thursday it had received $30 million in funding from investors including the firm that manages Amazon founder Jeff Bezos's venture investments and an investment arm of the Central Intelligence Agency.

The investments, from Bezos Expeditions and In-Q-Tel, mark a vote of confidence in the potential for practical applications for the emerging technology underpinning quantum computing.

Advocates say the controversial technology works orders of magnitude faster than classical computing and has the potential to revolutionize fields such as drug development. It has remained mainly an academic concept since its introduction 30 years ago, but investors see new commercial opportunities.

Last year, D-Wave sold a $10 million superconducting-based quantum computer to Lockheed Martin , which installed it at the University of Southern California. This year, it hopes to sell a much more powerful version.

It is also marketing its own quantum-computing capability to other companies, which can tap into D-Wave's facilities using cloud computing, or remote servers. D-Wave chief executive Vern Brownell describes it as infrastructure-as-a-service, adding the company inked its first contract in the area a few weeks ago.

The company's technology is controversial in the scientific community, in part because D-Wave places a premium on working at large-scale rather than perfect error correction.

Some scientists question whether it is quantum computing at all, but D-Wave Brownell dismisses the skeptics.

"It's very simple to determine if you've built a quantum computer or not," he says. "If your machine is running a quantum algorithm - that is, a problem solving a procedure forbidden by the laws of classical physics but permitted by quantum mechanics - it's a quantum computer."

Quantum computing as his company handles it is useful only in certain areas, Brownell said. He sees the main applications for D-Wave as defense and intelligence, bio-informatics, analytics for large Internet companies such as Google, which works with D-Wave on projects such as teaching machines to recognize images of cars, and financial services.

Currently, researchers at the University of Southern California are still testing the D-Wave computer's quantum capabilities to verify that it works faster and more efficiently than classical computing, said USC engineer Sergio Boxio.

They are working on areas such as machine learning, including improving the efficiency of solar cells, general computer-science problems such as complex scheduling, and minimizing errors in encoded messages such as those sent between a mobile phone and a tower.

For Lockheed, the hope is that D-Wave's technology can one day handle software verification and validation much faster than the company can do it now-a big task for a company that must exhaustively test for bugs every time it, say, updates software in flight-navigation systems.

Others are working on quantum-computing technology with more general applications.

IBM, for example, has dedicated researchers in the field at a research facility in Yorktown Heights, NY, working on superconducting-based quantum technology. IBM uses a different technique compared with D-Wave's adiabatic process, which means there is no heat transfer.

Earlier this year, IBM's researchers announced a breakthrough that lengthened the lifespan of quantum bits of information and made the technology work faster, with less error.

Meanwhile, researchers at Cambridge University announced a breakthrough in another variety of quantum-computer technology that relies on lasers.

Scientists at institutions including the National Institute of Standards and Technology are working on an ion-based quantum-computing technology. Other organizations are exploring quantum computing based on nuclear magnetic resonance.

"Over the next few years, we'll probably learn a lot more about which system is the front-runner," said Matthias Steffen, manager of IBM's experimental quantum computing group. "It's too early to tell."